(a) Raman spectra of monolayer, AB-stacked bilayer and ABA-stacked trilayer graphene transferred onto SiO2/Si substrates. The absence of D peak(s) (at 1350 cm-1) demonstrates the high quality of these graphene sheets. (b) Lorentzian fit of the 2D peaks for monolayer, AB-stacked bilayer and ABA-stacked trilayer graphene films. (c-k) Optical images and Raman maps of bilayer islands, a continuous bilayer film, and a trilayer graphene film. The uniformity of the maps indicates that the bilayer islands are AB-stacked and single crystal. The monolayer regions are green, and the multilayer regions red. Increasing the growth time transforms the bilayer islands (c, d, e) into a nearly continuous bilayer graphene film (f, g, h).